Method and System for Establishing Wireless IP Connectivity

ABSTRACT

A method and system for establishing wireless IP connectivity, in which a wireless communication device (WCD) obtains a routable IP address during its registration with a radio access network, rather than first registering with the RAN and then subsequently requesting and acquiring packet-data connectivity. Preferably, when the WCD sends a radio access registration request that triggers a registration notification to a home location register (HLR), the HLR or an associated entity will assign an IP address for use by the WCD and will deliver the assigned IP address in a registration notification response message to the RAN. The RAN will then deliver the assigned IP address to the WCD over the air in a radio access registration response message. The WCD may then use the assigned IP address to engage in packet data communications, such as to set up a VoIP session with another IP node, for instance.

REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 12/432,418,filed Apr. 29, 2009, which is a continuation of U.S. patent applicationSer. No. 10/986,620 (issued as U.S. Pat. No. 7,567,804), filed Nov. 12,2004. These priority applications are hereby incorporated by referencein their entirety.

FIELD OF THE INVENTION

The present invention relates to wireless communications and, moreparticularly, to cellular wireless packet data communications. Theinvention can be usefully employed to facilitate establishment ofend-to-end voice-over-IP (VoIP) connectivity from a cellular wirelesscommunication device such as a cell phone. Further, the invention canextend to other arrangements as well.

BACKGROUND

It is generally known for a cellular wireless communication device (WCD)to engage in voice calls via a cellular radio access network (RAN). Atraditional RAN includes one or more mobile switching centers (MSCs),each of which is connected with one or more base station controllers(BSCs), and each BSC is in turn connected with one or more basetransceiver stations (BTSs) that define cellular wireless coverage areasin which wireless communication devices can operate.

Typically, each BTS includes an antenna tower with antennas arranged toradiate in a desired pattern so as to produce a desired level ofcoverage, defining a cell and a number of cell sectors. Each BSC thenfunctions to manage air interface communications, such as to assign airinterface traffic channels over which WCDs can communicate, and tomanage handoff of communications as a WCD moves between coverage areas(e.g., sectors). Each MSC, in turn, functions as a switching point, toprovide connectivity between various WCDs in its coverage, and betweenWCDs and the public switched telephone network, and further tofacilitate handoff of communications as a WCD moves between BSC servingareas or MSC serving areas.

Conventionally, each WCD has an assigned identifier, such as a mobileidentification number (MIN) or mobile directory number (MDN), and eachWCD has a service profile stored in a home location register (HLR). EachMSC is in turn coupled with the HLR, typically by an out of bandsignaling network such as a Signaling System #7 (SS7) network forinstance.

When a WCD powers on in, or otherwise enters, a coverage area (such asan area served by a particular BTS, BSC, or MSC), the WCD will registerwith the radio network infrastructure, so the system can know where theWCD is located (e.g., for purposes of directing calls to the WCD) and sothe system can verify that the WCD is authorized to engage in wirelesscommunications. In a typical radio network registration process, the WCDsends a radio access registration message over the air to the RAN and,assuming successful registration, then receives a radio accessregistration response message from the RAN. Further, during a typicalradio network registration process, the HLR will deliver a copy of theWCD's service profile to the serving MSC, so that the MSC can thenreference the profile when serving the WCD.

In a system compliant with the well known CDMA (e.g., CDMA2000) andIS-41 protocols, for example, a WCD engages in radio networkregistration by sending over the air (in an air interface accesschannel) to the BTS and, in turn to the BSC, an “access probe,” whichcarries an identifier of the mobile station and other pertinentinformation. When the BSC receives the access probe, the BSC passes theaccess probe along to the MSC, and the MSC then sends an IS-41“Registration Notification” (REGNOT) message to the HLR. The HLR in turnupdates the WCD's profile to indicate where the WCD is operating (e.g.,which MSC is serving the WCD) and may further carry out anauthentication process, and the HLR then sends an IS-41 registrationnotification return result (regnot_rr), typically including the WCD'sservice profile, to the MSC. The MSC then sends a registrationacknowledgement over the air (in an air interface paging channel) to theWCD to complete the registration process.

Once the WCD is registered with the RAN, the WCD can then place andreceive voice calls (assuming the WCD's service profile andconfiguration allow it). To place a call, for instance, the WCD may senda call origination message over the air (in an air interface accesschannel) to the RAN, providing a set of dialed digits indicative of acalled party phone number. Upon receipt of the call origination message,the MSC may then direct the BSC to assign an air interface trafficchannel for use by the WCD, and the MSC may further engage in call setupsignaling (e.g., ISDN User Part (ISUP) signaling) to set up the callwith a remote switch serving the called party. When the called partyanswers, the MSC may then connect the call through to the WCD.Similarly, when the MSC receives a request to connect an incoming callto the WCD, the MSC may page and alert the WCD over the air (in an airinterface paging channel). When the WCD answers the call, the MSC maythen connect the call through to the WCD.

One of the important features of many RAN systems is the ability tomanage WCD mobility, such as handoff of calls from one coverage area toanother as a WCD moves between coverage areas. As noted above, a BSCtypically serves this function for handoffs between coverage areas(e.g., sectors) that the BSC serves. For handoffs between BSCs, on theother hand, IS-41 defines a process in which the BSC that first handlesthe call (the “anchor” BSC) remains in the call path, and bearer trafficis shunted between that anchor BSC and the BSC currently serving theWCD, so as to maintain connectivity as the WCD moves between BSCcoverage areas.

It is also generally known today for WCDs to be able to engage inwireless packet data communication. In a system compliant with the wellknown CDMA2000® protocol, for instance, a WCD (such as a cell phone,wirelessly equipped PDA, or wirelessly-equipped computer) can obtainpacket data connectivity by signaling with the RAN and by signalingthrough the RAN with a packet data serving node (PDSN) that sits as agateway on a packet-switched network.

In particular, after the WCD enters a wireless coverage area andsuccessfully engages in radio network registration, the WCD can send apacket-data origination message via an air interface access channel tothe RAN. Under CDMA2000®, the packet-data origination message may belargely the same as a traditional call origination message, except thatit would include a special service option code that signifies a requestto establish packet-data connectivity. Upon receipt of the packet-dataorigination message, a BSC or other radio network controller (RNC) inthe RAN may then assign an air interface traffic channel for use by theWCD as a radio link, and the RAN may signal to a PDSN to triggerestablishment of a data link, such as a point-to-point protocol session(i.e., a serialized packet-data connection), between the PDSN and theWCD. Once that data link is established, the WCD may then send amobile-IP registration request to the PDSN, which the PDSN may forwardto a mobile-IP home agent, and the home agent may then assign an IPaddress for use by the WCD to engage in communications on thepacket-switched network.

It is further known for WCDs to be able to engage in voice-over-IP(VoIP) and other packet-based real-time media communications. Forexample, after a WCD gains radio access and then packet dataconnectivity as described above, the WCD may engage in call setupsignaling, such as Session Initiation Protocol (SIP) signaling or H.323signaling for instance, to set up a packet-based real-time media sessionwith another entity on the packet-switched network. Such a session couldcarry media according to the well known Real-time Transport Protocol(RTP), as described in RFC 1889, or in some other manner.

When a WCD engages in wireless packet data communications, andparticularly packet-based real-time media communications such as VoIP,an additional mobility management issue arises. In particular, as a WCDmoves between PDSN serving systems, the WCD must establish connectivitywith the new PDSN, and the mobile-IP home agent must be informed thatthe new PDSN is serving the WCD. In some cases, this process of handingoff to a new PDSN can take on the order of 6 seconds to complete, whichmay unfortunately disrupt real-time media communications.

SUMMARY

The present invention provides an improved arrangement and process thathelps to avoid the foregoing problem. According to the invention, a WCDwill obtain a routable network address (e.g., IP address) during itsregistration with the RAN, rather than first registering with the RANand then subsequently requesting packet-data connectivity. In accordancewith an exemplary embodiment of the invention, for instance, when theWCD sends a radio access registration request that triggers aregistration notification to the HLR, the HLR or an associated entitywill assign a network address for use by the WCD and will deliver theassigned network address in a registration notification response messageto the RAN. The RAN will then deliver the assigned network address in aradio access registration response message over the air to the WCD, foruse by the WCD to engage in communications on a packet-switched network.

Further according to the exemplary embodiment, the RAN will providedirect packet-data connectivity with the packet-switched network. In apreferred arrangement, for instance, the BSC (or another RNC) willitself sit as a node on the packet-switched network, so packet data canflow more directly (i) over the radio link between the WCD and the BSCand (ii) between the BSC and other entities on the packet-switchednetwork, without the need for a PDSN to sit between the RAN and thepacket-switched network.

In place of the traditional MSC will also be a media gateway controller(MGC), known in the art as a “softswitch,” which also sits as a node onthe packet-switched network. The MGC, like a conventional MSC, will havea signaling link (e.g., an SS7 network) with the HLR and with otherswitching points. Further, as a node on the packet-switched network, theMGC can engage in communication with other entities on thepacket-switched network.

In the preferred arrangement, a WCD will send a radio accessregistration message over the air to the BSC, which the BSC will forward(over the packet-switched network) to the MGC. As a conventional MSCwould do, the MGC will then send a registration notification message(e.g., an IS-41 REGNOT) to the HLR. At this point, however, the HLR oranother entity will then assign a network address (e.g., IP address) foruse by the WCD and will deliver the assigned network address in aregistration notification response message (e.g., an IS-41 regnot_rr) tothe MGC. Upon receipt of that response, like a conventional MSC, the MGCwill then send a radio access registration response message to the WCD.But in accordance with the exemplary embodiment, the MGC will includethe assigned network address in the radio access registration responsemessage. Thus, when the WCD receives the radio access registrationresponse acknowledging successful registration with the RAN, the WCDwill receive in the response its newly assigned network address.

In accordance with a further aspect of the exemplary embodiment, oncethe WCD has completed its radio access registration and thereby acquireda network address, the WCD may then work to set up a packet-basedreal-time media communication session with a remote endpoint on thepacket-switched network. If the WCD already has a network address of theremote endpoint, the WCD may simply engage in call setup signaling, suchas SIP signaling or H.323 signaling, with the remote endpoint toestablish the session. Alternatively, if the WCD has only a telephonenumber or other such identifier of a called party, a variation on thetraditional call setup process can be used to provide the WCD with anetwork address of the remote endpoint, so that the WCD can then engagein call setup signaling with the remote endpoint to set up the session.

In an exemplary call setup variation, the WCD will send a traditionalcall origination message to the MGC (just as it would send a callorigination message to an MSC), providing the MGC with a telephonenumber (or other identifier) of the called party. Yet, the WCD willinclude in the call origination message a special service option codethat designates the call request as an address-translation request,rather than as a traditional call setup request. In response todetecting the special service option code in the call request, the MGCwill then work to translate the dialed digits into a network address ofa remote endpoint serving the called party. For instance, the MGC mayquery an address mapping system (AMS), such as an ENUM server. The MGCwill then send a traditional call origination response message to theWCD, but the MGC will include in the call origination response message(e.g., in a user-definable field) the network address of the remoteendpoint. Given its own network address (assigned during radio accessregistration) and given the network address of the remote endpoint, theWCD may then engage in call setup signaling (e.g., SIP signaling) to setup a packet-based real-time media session with the remote endpoint.

Advantageously, by assigning an network address to a WCD during theradio access registration process, and by providing a direct connectionbetween the radio access network and the packet-switched network, theWCD can more seamlessly engage in packet-based real-time mediacommunications and other sorts of packet-data communications. Without aPDSN in the communication path, no need arises to hand off sessionsbetween PDSNs as the WCD moves from one coverage area to another, andthus the potentially substantial delay of inter-PDSN handoff can beavoided. Instead, what remains can be the traditional process of handingoff from one BSC to another, in which the anchor BSC remains in the callpath. (In an alternative embodiment, a PDSN or another such gateway cannevertheless remain in the call path. However, the WCD would stillacquire its network address during the radio access registrationprocess.)

These as well as other aspects, advantages, and alternatives will becomeapparent to those of ordinary skill in the art by reading the followingdetailed description, with reference where appropriate to theaccompanying drawings. Further, it should be understood that theembodiments described in this summary and elsewhere are intended to beexamples only and do not necessarily limit the scope of the invention asclaimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a communication system in which anexemplary embodiment of the invention can be implemented.

FIG. 2 is a flow chart depicting functions carried out in accordancewith the exemplary embodiment to assign a network address to a WCDduring radio access registration.

FIG. 3 is a flow chart depicting functions carried out in accordancewith the exemplary embodiment to facilitate session setup after the WCDhas acquired a network address during radio access registration.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

Referring to the drawings, FIG. 1 is a simplified block diagramdepicting the arrangement of a communication system 10 in which anexemplary embodiment of the invention can be implemented. It should beunderstood, however, that these and other arrangements and processesshown and described herein are provided as examples only, and that manyvariations are possible. For instance, elements can be combined,distributed, omitted, added, or re-ordered. Further, the various logicfunctions described herein can be carried out by any combination ofhardware, firmware and/or software, such as by one or more suitablyprogrammed processors (e.g., one or more processors, data storage, andprogram instructions stored in the data storage and executable by theprocessor(s)), for instance.

As shown in FIG. 1, the communication system 10 includes a radio accessnetwork (RAN) 12, which includes, by way of example, a base transceiverstation (BTS) 14 coupled with a base station controller (BSC) or otherradio network controller (RNC) 16. Although only one BTS and one BSC areshown, the RAN could equally include a plurality of BTSs and a pluralityof BSCs. As explained above, each BTS radiates to define one or morewireless coverage areas, such as cells and cell sectors, in whichwireless communication devices can communicate with the BTS, and eachBSC manages air interface communications with one or more BTSs. FIG. 1depicts an example wireless communication device (WCD) 18 communicatingover a radio frequency air interface 20 with BTS 14, or more generallywith RAN 12.

BSC 16 is, in turn, coupled with a packet-switched network 22. Moreparticularly, in the exemplary embodiment, BSC 16 sits as a node onpacket-switched network 22. Thus BSC 16 is both an element of RAN 12 anda node on packet-switched network 22 (notwithstanding that the figureshows BSC 16 inside the cloud of RAN 12 and outside the cloud of network22). BSC 16 may be tied to packet-switched network through conventionalmeans, such as an Ethernet connection for instance, and possibly througha gateway function integrated with the BSC or located external to theBSC.

Packet-switched network 22 may include a wireless carrier's core packetnetwork, i.e., a packet-data network over which a wireless carriertransports various traffic, such as signaling traffic and/or bearertraffic. Packet-switched network 22 may further include or interconnectwith a public packet data network, such as the Internet, and/or one ormore other networks, whether public or private. In a preferredembodiment, packet-switched network 22 carries traffic compliant withthe well known Internet Protocol, so each entity that communicates onthe network 22 would have an IP address. Other network and transportprotocols could be used instead or in addition, however.

As further shown in FIG. 1, packet-switched network 22 providesconnectivity with various remote endpoints, each equipped to communicateon the network, e.g., through IP communication. By way of example, thenetwork 22 may provide connectivity with a remote gateway (e.g., a mediagateway, IP telephony gateway, media terminal adapter, or the like) 24,which serves one or more telephone devices such as the example telephone26 as shown. More particularly, gateway 24 may translate between legacy,circuit-switched communications with telephone 26 and packet-switchedcommunications on network 22, to allow telephone 26 to place and receivecalls over network 22. As other examples, network 22 may provideconnectivity with an IP telephone device 28 and/or a multimedia computer30, or for that matter with any other device adapted to communicate onnetwork 22, whether the device is connected through landline and/orwireless links. (Although FIG. 1 depicts these endpoints on the otherside of network 22, the endpoints could equally be served by RAN 12 aswell, i.e., as other wireless communication devices.)

Additionally shown as a node on network 22, or accessible throughnetwork 22, is an address mapping system (AMS) 32, which can be arrangedin a manner well known in the art to be able to translate betweentelephone numbers (or other identifiers) and network addresses, so as tofacilitate IP telephony and the like. By way of example, AMS 32 can bean ENUM server or other address mapping system that includes dataindicating mappings between telephone numbers and IP addresses and thatincludes a server function that can receive and respond to mappingrequests based on the mapping data.

Further shown as a node on packet-switched network 22 is a media gatewaycontroller (MGC) 34, which, as noted above, is also known in the art asa softswitch. MGC 34 is in turn coupled with a signaling network 36.Signaling network 36 may itself be a packet-switched network and may infact be the same network as network 22 and/or may overlap in part withnetwork 22. Signaling network 36 may be an out of band signalingnetwork, in that it may support signaling communication according to aprotocol such as the well known Signaling System #7 (SS7) for instance.As such, signaling network 36 may include a number of signal transferpoints (STPs) (not shown) that function to route signaling traffic frompoint to point. Further, as shown, signaling network 36 providesconnectivity with a home location register (HLR) 38

MGC 34 functions largely as an MSC, to support communications by devicessuch as WCD 18. (Although MGC is shown outside of the RAN cloud 12, MGC34 could equally be illustrated in that cloud, since it functions as anelement of the RAN.) As such, like a traditional MSC, MGC 34 may receivea registration message when WCD 18 enters a designated wireless coveragearea, and MGC 34 may responsively send a registration notificationmessage (e.g., an IS-41 REGNOT message) via signaling network 36 to HLR38. In turn, MGC 34 may receive from HLR 38 a registration notificationreturn message (e.g., an IS-41 regnot_rr), which may carry a serviceprofile for WCD 18, and MGC 34 may store the service profile in avisitor location register (VLR) (not shown) for later reference and senda radio access registration response message to WCD 18. Further, MGC 34may function as a switching point to set up calls over the PSTN (notshown) or over one or more other transport networks for WCD 18.

As noted above, in accordance with the exemplary embodiment, a WCD willacquire a network address during radio access registration, i.e., aspart of its radio access registration process, rather than firstregistering with the radio access network and then seeking to acquirepacket-data connectivity. In a preferred arrangement, this will beaccomplished by having the HLR or an associated entity assign thenetwork address and deliver the assigned address in a registrationnotification response message. However, the assignment of networkaddress during radio access registration can be accomplished in otherways as well.

To facilitate assignment of a network address in the preferredembodiment, a Dynamic Host Configuration Protocol (DHCP) server function40 will be provided in association with HLR 38, as shown in FIG. 1. Byway of example, the DHCP server function 40 can be a function of the HLRitself, such as through program logic executed by the HLR.Alternatively, the DHCP server function 40 can be provided separatelyfrom the HLR, in a manner that allows the HLR to obtain a networkaddress for WCD 18 from the DHCP server function. Optimally, the DHCPserver function 40 can include a centralized DHCP server (not shown),located on packet-switched network 22 for instance, which functions toassign IP addresses for communication on network 22. DHCP proxies (notshown) can then be provided elsewhere, functioning to pass DHCPcommunications between the DHCP server and an entity requesting anetwork address, such as HLR 38.

As is well known in the art, a DHCP server operates to dynamicallyassign IP addresses (or other network addresses, for that matter) toDHCP clients. Conventionally, a DHCP client would broadcast a DHCP“DISCOVER” packet, in response to which a DHCP server would send a DHCP“OFFER” packet. The DHCP client would then send to that DHCP server aDHCP “REQUEST” packet, providing the server with the client's MACaddress and requesting an IP address. In turn, the DHCP server thenselects an IP address from a pool of available IP addresses, and sends aDHCP “ACK” packet to the client, providing the client with the assignedIP address (typically to be used for a limited period of time), and theserver records the fact that the address is assigned to that client.

According to the exemplary embodiment, when the HLR 38 receives aregistration notification message that requests, provides notice of,and/or otherwise indicates radio access registration of WCD 18, the HLRwill invoke the DHCP server function 40 so as to have an IP addressassigned for the WCD. To do this, for instance, the HLR mayprogrammatically call the DHCP server function, passing to the DHCPserver function a WCD that was conveyed in the registration notificationmessage from RAN 12. More particularly, the HLR may send a DHCP REQUESTpacket to the DHCP server function. The DHCP server function 40 may thenassign an IP address for use by WCD 18 to communicate on packet-switchednetwork 22 and may deliver that IP address to the HLR in a DHCP ACKpacket. Alternatively, the HLR or some other associated entity couldotherwise select an IP address from a pool of available IP addresses,and assign the selected IP address for use by the WCD.

Note that the HLR 38 may carry out this function after the WCD is firstauthorized for service in the RAN. By way of example, once the HLR 38receives a registration notification message from MGC 34, the HLR,either alone or in combination with an authentication center (notshown), can work conventionally to authenticate the WCD 18 so as toensure that WCD 18 is entitled to have radio network access. Once thatauthentication process is complete, the HLR may then invoke the DHCPfunction 40 or otherwise assign, or have assigned, an IP address for useby WCD 18. Alternatively, the HLR may invoke the address-assignmentfunction before or concurrently with the authentication function.

FIG. 2 next provides a flow chart depicting functions carried out toassign a network address to WCD 18 during its radio access registrationprocess, in accordance with the exemplary embodiment. As shown in FIG.2, at block 50, a wireless carrier (e.g., cellular service provider) orother entity wirelessly receives into RAN 12 from WCD 18 a radio accessregistration request message seeking to register WCD 18 for wirelesscommunication in the RAN. In a CDMA system, for instance, this functioncan involve receiving one or more access probes transmitted in an airinterface access channel from the WCD.

At block 52, the wireless carrier then assigns a network address,preferably an IP address, to WCD 18, for use by the WCD to engage incommunications on packet-switched network 22. This function may occur,for instance, after MGC 34 sends a registration notification message toHLR 38 in response to the radio access registration request message, andpossibly after the HLR 38 and/or an authentication center completesauthentication of the WCD. Further, as noted above, this function mayinvolve the HLR or another entity invoking a DHCP server function (orother IP address assignment function) to assign an IP address for use bythe WCD. Alternatively, this function could occur at some other pointduring the radio access registration process. For instance, MGC 34itself could be set to assign an IP address to the WCD (e.g., applyingor otherwise invoking a DHCP server function or the like) or to invokean address-assignment function.

At block 54, the wireless carrier in turn transmits to the WCD 18 fromRAN 12 a radio access registration response message that (i)acknowledges registration of WCD 18 for wireless communication servicein the RAN and (ii) specifies the assigned network address for use bythe WCD. In a CDMA system, for instance, this function may involvesending the radio access registration response message in one or morefields of an air interface paging channel message, setting forth in theregistration response message (e.g., in one or more user-definablefields) the assigned IP address. Further, in an arrangement where theHLR 38 assigns (or causes to be assigned) an IP address for use by theWCD, the HLR could set forth the IP address in a registrationnotification response message or any other sort of message that the HLRsends to MGC 34, and MGC 34 may then include that assigned IP address inits radio access registration response message to the WCD. In apreferred embodiment, the IP address would be set forth in a predefinedfield of the radio access registration response message, whether thatfield is currently available user-definable field or a newly addedfield.

As further noted above, in accordance with the exemplary embodiment,after a WCD has acquired a network address during radio accessregistration, the WCD may then conveniently use its network address toenter into various packet-data communications. In the arrangement ofFIG. 1, for instance, after WCD 18 has acquired an IP address during itsradio access registration, WCD 18 may use the IP address to engage incommunications with endpoint nodes such as IP telephone 28, gateway 24,and/or computer 30. In a preferred embodiment, for example, WCD 18 mayengage in IP-based session setup signaling with one or more of these (orother) entities to establish a packet-based real-time media session,such as an RTP session.

Mechanics for setting up a packet-based real time media session are wellknown in the art and therefore are not described here in great detail.Merely as an example, either of the well known SIP protocol or H.323protocol could be used to set up such a session.

With SIP, for instance, each endpoint typically has an assigned “SIPaddress” (usually in the form username@realm). When an endpoint goesonline, it may register with a SIP registration server, to give theserver a correlation between its SIP address and its IP address, so asto facilitate routing of signaling message to its SIP address. Aspresently contemplated, after WCD 18 acquires an IP address during radioaccess registration, WCD 18 may thus register with a SIP registrationserver (not shown) on packet-switched network 22, to give the server acorrelation between its assigned IP address and its SIP address (or aSIP address of a user of WCD 18).

To initiate a packet-based real-time media session with a remoteendpoint on network 22, WCD 18 may then send a SIP “INVITE” message tothe SIP address of that endpoint, describing in the SIP INVITE messagethe type of session desired. If the remote endpoint agrees toparticipate in the session, it may then return to WCD 18 a SIP “200 OK”message, indicating its agreement. In turn, WCD 18 may complete sessionsetup by sending a SIP “ACK” to the remote endpoint. (Alternatively, theremote endpoint may initiate a packet-based real-time media session withWCD 18, by sending a SIP INVITE to WCD 18, and so forth.) By thissignaling process, WCD 18 and the remote endpoint may work to set up anRTP session or other packet-based real-time media session, carryingvoice (e.g., VoIP), video, and/or any other media between their IPaddresses.

With H.323 (and its associated protocols, such as H.225 and H.245), WCD18 may similarly initiate a packet-based real-time media conferenceafter acquiring its IP address. By way of example, WCD 18 may first sendan H.225 Call Setup Request from its IP address to the IP address of theremote endpoint. In response, the remote endpoint may then send an H.225OK message to WCD 18. WCD 18 may then send an H.245 Open Media Requestto the remote endpoint, and the remote endpoint may respond with anH.245 Open Media OK. And WCD 18 and the remote endpoint may thensimilarly begin exchanging media, such as voice and video, with eachother between their respective IP addresses.

In some cases, WCD 18 may already know the SIP address or IP address ofthe remote endpoint and may thus be able to conveniently initiatepacket-based real-time media sessions with the remote endpoint. (Forinstance, WCD 18 may have a local directory with an entry that lists theendpoint's SIP address or IP address. When a user of WCD 18 seeks tocall the endpoint by selecting the entry from the directory, WCD 18 maythen initiate session setup signaling with the endpoint's SIP address orIP address.)

In other cases, however, all WCD 18 may have is a telephone number orother identifier of the remote endpoint, but not a SIP address, IPaddress, or other network address at which WCD 18 can engage in sessionsetup signaling. For instance, a user of WCD 18 may input just thetelephone number of a remote device (such as telephone 28, telephone 26,or computer 30) or may select a directory listing that specifies just atelephone number of the device. In accordance with the exemplaryembodiment, in order to provide WCD 18 with a network address of theremote endpoint, a variation on the conventional call originationprocess can be used, as generally illustrated by FIG. 3.

As shown in FIG. 3, at block 60, WCD 18 first acquires an IP addressduring its radio access registration process, as described above. Atblock 62, a call controller then receives from the WCD an originationrequest seeking to establish a call (i.e., real-time media session) to acalled party. In the preferred embodiment, the call controller will beMGC 34. Further, the origination request will preferably be aconventional IS-41 call-origination request that carries dialed digitsrepresenting the called party. (As is known in the art, “dialed digits”may or may not be actually “dialed” and may further include one or morenumerals and/or one or more other characters.) Like other signaling toMGC 34, the origination request may thus pass over the air to RAN 12and, in turn, over packet-switched network (over IP) to MGC 34.

In the variation as presently contemplated, the origination request toMGC 34 will carry a special service-option code, which MGC 34 will treatas an indication that the origination request is an address-translationrequest. In response to the address-translation request, MGC 34 willthen engage in an address-translation process, at block 64, so as todetermine a network address at which WCD 18 can engage in session-setupsignaling so as to set up the call to the called party. For instance,MGC 34 may send an address-translation request via packet-switchednetwork 22 to AMS 32, providing AMS 32 with the dialed digits that werecarried in the request from WCD 18. AMS 32 may then perform a lookup todetermine a SIP address, IP address, or other network address of aremote endpoint serving the dialed digits, such as an address onpacket-switched network 22 of IP telephone 28, gateway 24 (servingtelephone 26), or computer 30. And AMS 32 may then return that networkaddress to MGC 34 in a response message. In an alternative arrangement,MGC 34 itself, or some other entity, can perform the addresstranslation.

At block 66, MGC 34 may then send the determined network address of theremote endpoint to WCD 18 in a call origination response message. In apreferred embodiment, the determined network address would be set forthin a predefined field of the call origination response message, whetherthe field is a currently available user-definable field or a newlydefined field. At block 68, the wireless carrier may then transport callsetup signaling that is being communicated between the IP address of theWCD 18 and the determined network address of the remote endpoint. Thatis, session setup signaling, such as SIP signaling or H.323 signalingfor instance, will pass through the wireless carrier's system (e.g., RAN12) as it flows between WCD 18 and the remote endpoint. As a result, atblock 70, a packet-based real-time media session (such as a VoIPsession, for instance), will be established between WCD 18 and theremote endpoint.

As noted above, by assigning a network address to WCD 18 during itsradio access registration process and, preferably, by giving BSC 16 adirect connection with packet-switched network 22, conventional mobilitymanagement techniques can be used to manage handoff of the resultingreal-time media session. For instance, as WCD 18 moves from the coveragearea of BSC 16 into the coverage area of another BSC (not shown), BSC 16can remain the anchor BSC, and session traffic can be shunted betweenthe BSC 16 and the currently serving BSC.

An exemplary embodiment of the present invention has been describedabove. Those skilled in the art will understand, however, that changesand modifications may be made to this embodiment without departing fromthe true scope and spirit of the invention, which is defined by theclaims.

1. A method comprising: wirelessly receiving into a cellular radioaccess network (RAN) from a wireless communication device (WCD) a radioaccess registration message seeking to register the WCD for wirelesscommunication service in the RAN; in response to the radio accessregistration message from the WCD, sending a registration notificationmessage from the RAN to a home location register (HLR) that serves theWCD, the HLR including or having access to an Internet Protocol (IP)address assignment function; responsive to the registration notificationmessage, (i) IP address assignment function assigning an IP address tothe WCD, for use by the WCD to engage in communications on apacket-switched network (ii) the HLR generating a registrationnotification response message, and (iii) including the assigned IPaddress in the registration notification response message, and (iv)sending the registration notification response message, including theassigned IP address, to the RAN; and upon receipt of the registrationnotification message including the assigned IP address, wirelesslytransmitting to the WCD from the RAN, in response to the radio accessregistration message, a radio access registration response message,wherein the radio access registration response message acknowledgesregistration of the WCD for wireless communication service in the RANand specifies the assigned IP address for use by the WCD.
 2. The methodof claim 1, wherein wirelessly receiving into the RAN from the WCD theradio access registration message seeking to register the WCD forwireless communication service in the RAN comprises receiving the radioaccess registration message in an access probe on an air interfaceaccess channel from the WCD.
 3. The method of claim 1, wherein the IPaddress assignment function comprises a DHCP server function.
 4. Themethod of claim 3, wherein the HLR includes the DHCP server function. 5.The method of claim 3, wherein the DPCP server function is external tothe HLR and provides the assigned IP address to the HLR for inclusion inthe registration notification response message.
 6. The method of claim1, wherein the registration notification message comprises an IS-41Registration Notification message, and the registration notificationresponse message comprises an IS-41 Registration Notification returnresult message.
 7. The method of claim 1, further comprising, aftertransmitting the radio access registration response message includingthe assigned IP address to the WCD: receiving into a call controllerfrom the WCD a call origination request seeking to establish a call to acalled party, and responsively sending to the WCD an IP address of aremote endpoint serving the called party; and transporting call setupsignaling that is being communicated between the assigned IP address ofthe WCD and the IP address of the remote endpoint, for setting up thecall as a packet-based real-time media session between the WCD and theremote endpoint.
 8. The method of claim 7, wherein the call controllercomprises a media gateway controller.
 9. The method of claim 7, whereinthe origination message comprises an IS-41 origination message, andwherein responsively giving the WCD an IP address of a remote endpointserving the called party comprises sending to the WCD an IS-41origination response message that specifies the IP address of the remoteendpoint.
 10. The method of claim 7, further comprising: in response tothe call origination request, determining the network address of theremote endpoint, before sending the network address of the remoteendpoint to the WCD, wherein determining the network address of theremote endpoint comprises querying an address mapping system, based ondialed digits provided in the origination request from the WCD.
 11. Themethod of claim 7, wherein the call setup signaling comprises signalingselected from the group consisting of Session Initiation Protocol (SIP)signaling and H.323 signaling.
 12. The method of claim 7, wherein theremote endpoint comprises an entity selected from the group consistingof (i) a remote gateway that serves a client station operated by thecalled party, and (ii) a client station operated by the called party.13. The method of claim 7, wherein the packet-based real-time mediasession comprises a voice-over-IP (VoIP) session.
 14. A methodcomprising: receiving into a radio access network (RAN), over an airinterface access channel from a wireless communication device (WCD), afirst registration message for registering the WCD in a cellularwireless coverage area; in response to the first registration message,sending from the RAN to a home location register (HLR) a secondregistration message indicating registration of the WCD in the cellularwireless coverage area; in response to the second registration message,assigning an Internet Protocol (IP) address for use by the WCD to engagein IP-based communications on a packet-switched network, and sendingfrom the HLR to the RAN a first registration response message thatacknowledges registration of the WCD in the cellular wireless coveragearea and that specifies the assigned IP address; in response to thefirst registration response message, sending from the RAN to the WCD asecond registration response message that acknowledges registration ofthe WCD in the cellular wireless coverage area and that furtherspecifies the assigned IP address; thereafter conveying IP-based callsetup signaling between the assigned IP address of the WCD and an IPaddress of the remote endpoint, for setting up a packet-based real-timemedia session between WCD and the remote endpoint.
 15. The method ofclaim 14, wherein the second registration message comprises an IS-41registration notification message, and wherein the first registrationresponse message comprises an IS-41 registration notification returnresult message.
 16. The method of claim 14, wherein the HLR includes orhas access to a Dynamic Host Configuration Protocol (DHCP) serverfunction, and wherein assigning the IP address for use by the WCDcomprises the DHCP server function assigning the IP address for use bythe WCD.
 17. A communication system comprising: a radio access network(RAN) including a base transceiver station (BTS) coupled with a radionetwork controller (RNC), wherein the BTS defines a wireless coveragearea in which wireless communication devices can wirelessly communicatewith the BTS; and a media gateway controller (MGC) in communication withthe RNC and further in communication with a home location register(HLR), wherein the MGC receives a radio access registration message froma wireless communication device (WCD) that is located within thecellular wireless coverage area, the radio access registration messageseeking registration of the WCD for air interface communication with theRAN, and wherein the MGC responsively sends a registration notificationmessage to the HLR, and wherein the HLR assigns an Internet Protocol(IP) address for use by the WCD and sends the assigned IP address in aregistration notification response message to the MGC, and wherein theMGC sends the assigned IP address in a radio access registrationresponse message to the WCD, whereby the IP address is assigned andprovided to the WCD during radio access registration of the WCD ratherthan in response to the WCD requesting packet-data connectivity afterregistering with the RAN.
 18. The communication system of claim 17,wherein, after sending the radio access registration response message tothe WCD, the MGC receives from the WCD a call origination requestmessage seeking to set up a call with a called party, and the MGCresponsively sends to the WCD a call origination response message thatspecifies an IP address of a remote endpoint that serves the calledparty, and wherein call setup is then communicated between the assignedIP address of the WCD and the IP address of the remote endpoint, forestablishing a packet-based real-time media session between the WCD andthe remote endpoint.
 19. The communication system of claim 18, whereinthe MGC determines the network address of the remote endpoint byquerying an address mapping system.
 20. The communication system ofclaim 17, wherein the BTS receives the radio access registration messagefrom the WCD in an access probe on an air interface access channel andforwards the radio access registration message, and wherein the MGCreceiving the radio access registration message comprise the MGCreceiving the radio access registration message forwarded from the BTS.